#include "Day5.h"

#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#include <numeric>
#include <cmath>
struct Point
{
    int x = 0;
    int y = 0;
};

//returns -1 or 0 or 1
static int IntComp_(int a, int b)
{
    return (b < a) - (a < b) ;
}

class Line
{
public:
    bool IsVertical() const { return p1.y == p2.y; }
    bool IsHorizontal() const { return p1.x == p2.x; }
    std::vector<Point> PointsBetween() const
    {
        std::vector<Point> pts;

        //find direction of x and y
        auto dx = IntComp_(p2.x, p1.x);
        auto dy = IntComp_(p2.y, p1.y);

        for (auto x = p1.x, y = p1.y;
            x != p2.x || y != p2.y;
            x += dx,y += dy)
        {
            pts.emplace_back(x, y);
        }
        pts.emplace_back(p2); //loop didn't include last point.
        return pts;
    }
    Point p1;
    Point p2;
};

static std::pair<std::vector<Line>, int> ReadLines_()
{
    int maxSize = 0;
    std::ifstream infile("5.txt");
    std::vector<Line> lines;
    Line line;
    std::string filler;
    char c1, c2;
    while (infile >> line.p1.x >> c1 >> line.p1.y >> filler >> line.p2.x >> c2 >> line.p2.y)
    {
        maxSize = std::max({ maxSize, line.p1.x, line.p1.y, line.p2.x, line.p2.y });
        lines.emplace_back(line);
    }
    return std::make_pair(lines, maxSize);
}

void day5::A()
{
    auto [lines, maxSize] = ReadLines_();
    std::vector<int> counts;
    counts.resize(maxSize* maxSize);//1000x1000 = 1,000,000

    for(const auto& line : lines)
    {
        if (line.IsVertical() || line.IsHorizontal()) //skip diagonal
        {
            for (const auto pt : line.PointsBetween())
            {
                auto index = pt.y * maxSize + pt.x;
                ++counts[index];
            }
        }
    }
    std::cout << "5A:" << std::count_if(counts.begin(), counts.end(), [](int i) {return i > 1; }) << "\n";
}

void day5::B()
{
    auto [lines, maxSize] = ReadLines_();
    std::vector<int> counts;
    counts.resize(maxSize * maxSize);//1000x1000 = 1,000,000

    for (const auto& line : lines)
    {
        for (const auto pt : line.PointsBetween())
        {
            auto index = pt.y * maxSize + pt.x;
            ++counts[index];
        }
    }
    std::cout << "5A:" << std::count_if(counts.begin(), counts.end(), [](int i) {return i > 1; }); << "\n";
}